P654: IBRUTINIB PLUS VENETOCLAX IN PATIENTS WITH COMPLEX KARYOTYPE AND CHRONIC LYMPHOCYTIC LEUKEMIA
Authors: A. Petrenko, M. Kislova, E. Dmitrieva, T. Novikova, M. Kislitsyna, T. Obukhova, E. Nikitin, V. Ptushkin
Journal: HemaSphere (2022)

Background: In the largest study of Baliakas et al. (2019) the presence of at least 5 abnormalities, was associated with dismal clinical outcome, independently of the somatic hypermutation status and TP53 status. The presence of 3 or 4 aberrations is defined as clinically relevant in the absence of TP53. Studies by Kittai (2021) and Al-Sawaf (2020) showed the impact of karyotypic complexity on survival in patients with chronic lymphocytic leukemia (CLL) treated with ibrutinib or venetoclax. The complex karyotype (CK) is a topic that is being intensively researched, both in the aspect of increasing karyotypic complexity stratification and clonal evolution. Optimal therapy for patients with CLL has not yet been developed. The combination therapy of ibrutinib and venetoclax was superior to chlorambucil and obinutuzumab in terms of undetectable minimal residual disease (MRD) responses according to data from the GLOW trial (Tunir, 2021). The importance of achieving a complete response with undetectable MRD as the goal of therapy in CLL was proposed (Montserrat, 2005). Aims: The aim of our study is to evaluate the effectiveness of therapy with ibrutinib and venetoclax in combination for the patients with CLL and CK. Methods: This ambilinear observational study included patients with CLL with high genetic complexity (high-CK), defined as >=5 aberrations or CK (>=3 aberrations) in combination with a 17p deletion (CK+del17p). The first retrospective cohort included patients treated with ibrutinib monotherapy (Imono) to progression or intolerable toxicity since May 2015. The second prospective cohort included patients receiving ibrutinib in combination with venetoclax (IVen) since July 2019. Venetoclax therapy was started at the 3rd month of ibrutinib (from the escalation phase). Combination therapy was continued until a complete response, defined as three consecutive PET-CT-negative and MRD-negative results 3 months apart. If this criterion was not achieved at 24th month of therapy, venetoclax was discontinued and ibrutinib continued indefinitely. Results: Seventy-nine patients are included in the study. Twenty-nine patients in the first cohort and 50 patients in the second cohort. The characteristic is presented in Table. At the current follow-up periods, there were no significant differences in PFS and OS regarding a follow-up period <= 24 months (with the exception of death from COVID-19, since patients were not observed at parallel time intervals). In the group of patients treated with Imono, the majority of patients achieved partial remission or partial remission with lymphocytosis by 12 months. In 21 patients from Iven group, with a median follow-up of 7.4 months, a complete remission was achieved (72.4%); of these, 8 had unmeasurable MRD. Four patients did not complete the escalation period. There was a significant difference in the median MRD response achieved between 3 (log10>10) and 12 (log10<0,1) months in IVen group (p=0,03). In 2 patient from the IVen group progression of the disease was noted. Image:Summary/Conclusion: Combination therapy with ibrutinib and venetoclax is an effective oral regimen for high-risk patients with complex karyotype disorders. PFS in both groups is currently not significantly different, which is obviously due to the short follow-up period. Patients receiving the IVen regimen achieve a significantly better response, which paves the way for allogeneic transplantation in these patients.